fibo.rb

class Fibo
  def calc(n)
    a = 0
    b = 1
    return [1] if n == 1

    result = [1]
    while a + b <= n
      result << a + b
      a = result[-2]
      b = result[-1]
    end
    result
  end
end

p Fibo.new.calc(100) #=> [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]